1. Field of the Invention
The present invention relates to magnetometers and, more specifically, to magnetometers based on micro-electromechanical systems (MEMS).
2. Description of the Related Art
Magnetometers are widely used in a variety of applications, such as extraterrestrial exploration, industrial process sensors, medical imaging equipment, scientific equipment, and detection of mineral deposits and submerged ships. Current trends in magnetometer design and development are toward smaller size, lower power consumption, and lower cost for a desired set of performance characteristics. Examples of prior-art miniature magnetometers can be found in U.S. Pat. Nos. 5,998,995, 5,731,703, and 5,644,230, the teachings of all of which are incorporated herein by reference.
One problem with prior-art miniature magnetometers is that they typically include strong micro-magnets, either permanent or electric. Permanent micro-magnets require magnetic (e.g., ferromagnetic and/or magnetostrictive) materials that are relatively difficult to process and integrate into the magnetometer structure with conventional micro-fabrication techniques. Micro-electromagnets, while relatively easy to manufacture, require passage of electrical current, which may cause excessive heating and/or unacceptably high power consumption. In addition, in a magnetometer having two or more magnetic sensors, the permanent or electric magnets of those sensors might interfere with each other, thereby distorting the measurement results generated by each of the sensors.